If you are looking for a spell to create a lightsaber, it may be theoretically possible, but practically impossible to do. The reason for this is that although matter has often been referred to as frozen energy, the sheer amount of energy that you would need is beyond almost everyone's ability and aura. If you were going down this path, you are better off capturing and storing energy in gemstones of a staff, sword or any other tool that you prefer, and after an extended period of time (which you should be able to feel and 'just know') you will be able to create something from (seemingly) nothing. Another possibility is that you could project energy in the shape of the beam, which you could do by raising the energy and forming it.
I wish you good luck, and hope that you don't die by overtaxing yourself, which creating something may do.